1. Field of the Invention
The invention relates to an adjusting device with a pneumatic cylinder in a printing press and, more particularly, a pneumatically operating piston-cylinder unit for actuating final control or adjusting elements in a printing press, the piston-cylinder unit, hereinafter also referred to as a pneumatic cylinder, being pressurized in the operating function thereof by partial action thereon and being lockable in the pressurized setting. The invention relates, in particular, to such a device for use in an arrangement for preventing the entry or in-feed of a mis-fed sheet or multiple sheets into a printing press.
The published German Patent Document DE 41 18 659 A 1 discloses an arrangement for actuating adjusting elements for starting and stopping printing in a sheet-fed printing press or for blocking the feeding of sheets, wherein latches which are able to be affected by electromagnets and by spring force are operatively associated with a lever which is pivotable about a fixed pivot point and connected to a drive member, and a piston-cylinder unit which is able to be acted upon hydraulically or possibly pneumatically, as well, for swivelling the lever after it has been unlocked, is provided, the piston-cylinder unit serving to swivel the lever, if mis-fed sheets are detected after the lever has been unlocked by the electromagnet, out of a relaxed or non-stressed zero or neutral position into a blocking position, wherein sheet grippers, for example, are blocked in the open position. For small-format pneumatic cylinders, the force is too low to re-open closed or partly-open grippers again, because they have to be quite small in order to travel the distance prescribed by the opening, within the shortest possible time. For electromagnets, the excitation time is very long, and the least force is available in the initial phase of the motion. The stroke of an electromagnet, under the prescribed conditions, is therefore limited. The physical conditions of a small pneumatic cylinder and of electromagnets have a particularly deleterious effect in high-speed printing presses.